U.S. Pat. No. 6,460,446—which is incorporated herein by reference as if set forth at length—is directed to a Sonic Rarefaction Wave Recoilless Gun System and issued on 8-Oct.-2002 to Eric L. Kathe and assigned to the assignee of the instant application. That patent describes a low-recoil and low-bore heat gun system that employs a delayed pressure release mechanism for fired propellant charges in the rear of a gun barrel. According to the patent, a delayed pressure release of exhaust gases causes a sonic rarefaction along the length of the gun barrel bore to arrive at an exit end of the gun barrel at a predetermined time, generally coincident with the fired projectile. As a result, such a gun system exhibits lower recoil without an appreciable loss of projectile velocity.
As can be readily appreciated, the delayed pressure release mechanism is a critical component of the Sonic Rarefaction Wave Recoilless Gun System, and essential to its operation. As described in the Sonic Rarefaction Wave Recoilless Gun System patent, the delayed pressure release mechanism comprises a physically heavy, bulky, and mechanically complex inertial breech.